values 13 values 13 (δ C ) within natural gas were found between the Shanxi and Benxi Formations: the δ C value of CO2 2 natural gas in the Shanxi Formation is generally less than -30‰, whereas that of the Benxi Formation is generally greater than -28‰; and CO in the Shanxi Formation is mainly of organic origin while that in the 2 13 Benxi Formation is mainly inorganic. The unusually depleted δ C values found in the Shanxi Formation were 2 caused by the addition of oil-type gas generated from the carbonate rock in the Taiyuan Formation, which 13 13 resulted in partial reversal of the carbon isotope values (δ C > δ C ). However, this incorporation of oil-type 1 2 gas did not occur in the Benxi Formation, which is most likely caused by the tight mudstone at the bottom of Taiyuan Formation. The differences between the Shanxi and Benxi Formations reveal that the gases in the two Formations belong to two separate gas systems, and this could be attributed to the tight mudstone and limestone existing between the reservoirs, which acts as an effective barrier preventing diffusion of gases.

Doucet, L.S., Li, Z.-X., Ernst, R.E., Kirscher, U., El Dien, H.G., Mitchell, R.N., 2019. Coupled supercontinent - mantle plume events evidenced by oceanic plume record. Geology 48, 159-163.

https://doi.org/10.1130/G46754.1 The most dominant features in the present-day lower mantle are the two antipodal African and Pacific large low-shear-velocity provinces (LLSVPs). How and when these two structures formed, and whether they are fixed and long lived through Earth history or dynamic and linked to the supercontinent cycles, remain first- order geodynamic questions. Hotspots and large igneous provinces (LIPs) are mostly generated above LLSVPs, and it is widely accepted that the African LLSVP existed by at least ca. 200 Ma beneath the supercontinent Pangea. Whereas the continental LIP record has been used to decipher the spatial and temporal variations of plume activity under the continents, plume records of the oceanic realm before ca. 170 Ma are mostly missing due to oceanic subduction. Here, we present the first compilation of an Oceanic Large Igneous Provinces database (O-LIPdb), which represents the preserved oceanic LIP and oceanic island basalt occurrences preserved in ophiolites. Using this database, we are able to reconstruct and compare the record of mantle plume activity in both the continental and oceanic realms for the past 2 b.y., spanning three supercontinent cycles. Time-series analysis reveals hints of similar cyclicity of the plume activity in the continent and oceanic realms, ∼ both exhibiting a periodicity of 500 m.y. that is comparable to the supercontinent cycle, albeit with a slight phase delay. Our results argue for dynamic LLSVPs where the supercontinent cycle and global subduction geometry control the formation and locations of the plumes.

Drake, P., 2020. Comment to 'More than ten years of Lusi: A review of facts, coincidences, and past and future studies' by Miller and Mazzini (2018): Taking the trigger debate above ground. Marine and Petroleum Geology 113, 104079.

http://www.sciencedirect.com/science/article/pii/S026481721930515X Since erupting in 2006, the 'Lapindo' mudflow (or 'Lusi,' as it is known by scientists) has released a constant flow of mud that has devastated communities and environments in East Java's Sidoarjo regency. The mudflow also has spawned countless formal and informal scientific reports that dispute what initiated the eruption: drilling for gas or a distant earthquake. A 2018 special issue in Marine and Petroleum Geology by the 'Lusi Lab' is devoted entirely to the mudflow, which includes an article by Miller a nd Mazzini (2018) that presents one perspective of the current status of the trigger debate. This discussion article draws attention to a series of inaccuracies and misrepresentations within Miller and Mazzini's (2018) article. These concerns include (1) t he promotion of erroneous drilling and geological data, (2) the inaccurate and unprofessional characterization of scientists who posit opposing interpretations of drilling and geological data, (3) the use of deceptive rhetoric, (4) the dissemination of misleading and unsubstantiated claims about unnamed stakeholders, and (5) the lack of knowledge of - and sensitivity toward - social contexts. After providing an overview of these issues, this article focuses on items (3), (4) and (5), which tend to be overlooked in ongoing geological discussions on the disaster, but have a significant impact on the production, circulation, and reception of geoscience in both professional and non-professional arenas. This commentary on Miller and Mazzini (2018) does not challenge the credibility or integrity of the authors or any scientist associated with the Lusi Lab, but rather argues for a version of geoscience that stays above ground by being conscientious to the social dynamics that impact, and are impacted